Hey there,

Obviously, you are an introvert and have self-esteem issues. I am by no means judging you for that, I simply state it as a fact, or at least a fair assumption. We are all different and that's fine. Having that in mind, I'm not going to tell you to "man up and be more assertive, or "don't give a damn about what anybody else tells you, believe in yourself" and that kind of crap. You are way, way too smart for that kind of cheap, self-motivating nonsense to work, and we all know it really doesn't work that way. We are what we are, so we play our best with the hand we are dealt.

A person like you is in constant search for validation. In order words, although you know how valuable, intelligent, well-educated and capable you are, you will get consumed by your feelings of unworthiness in presence of disproval, or even just absence of approval, of an authoritative figure. That's absurd, but it is what it is. Look how happy you are because of a performance award, and look how miserable you were with bad reviews from your previous dick of a manager. You were aware of all his failures as a manager and, yes, he did fail you in more ways that you could have ever failed him, and yet you felt really bad about yourself because you didn't live up to his expectations in a setting where expectations weren't even defined. You said it yourself.

It seems that you can only survive in a true meritocracy, where your true value can be shown and you could be fed a steady dose of kudos. Nothing wrong with that. Stay away from immature companies that don't seem to know what they want for themselves, let alone you. That being said, you probably don't want to be in a soul-searching, highly volatile start-up. You are probably better off in a well-defined system, with clearly set goals and success metrics, where your contributions can be valued objectively and with low margin of error. Yes, politics is everywhere, and your hyper-rational mind will struggle with that. Some people may get more kudos than you do because they present themselves and their work better than you, they are more vocal and make better relationships with their superiors. But, find a team and a manager who will know how to value you and everything that you're capable off, and you'll thrive. Ultimately, it is up to you to find an environment that is compatible with you and your expectations.

I really appreciate your humbleness and readiness to learn. It is very good for you to understand that constant learning is everything in our line of work and that perpetual hunger for knowledge will keep you sharp throughout your years. The issues that you're having are not rational ones, and there are people who can help you with them. It is probably much harder to find a good therapist that can guide you along the path of improvement of your self-esteem and self-valuation than to find a good tennis coach, but I guess it's much harder to conquer your demons than to learn how to play tennis. There is an almost natural disproportion between the level of classical, logical intelligence, and the emotional one, so that doesn't work in your favor, but it's manageable.

You are not entirely how you see yourself and you are not entirely what other claim you are, it's always in that gray area smart guys like us feel pretty uncomfortable with. Stay strong and find people who will value you for who you are, but don't forget to value yourself, even if they don't. You're one of the good guys, or girls, whatever.

P.S. A note on your "Edit 1" paragraph: I joined my current company with absolutely zero previous experience using Java and Linux experience. I'm writing Java on Linux now, using Spring and all those other things I harbor a hint of contempt for, being more of a C++ guy. So, when an "experienced engineer" tells you that your Spring should improve, he may be onto something iff you are really hunting for a job that actually requires proficiency in that, particular, technology. Otherwise, if you are dealing with serious companies who will value you for your strong CS fundamentals and the ability to think mathematically and algorithmically, they really don't give a damn if you don't speak their lingo yet, because they will see in you an innate ability to learn, even quicker than others and know that you'll ultimately be able to chew whatever they throw at you.